ABSTRACT
<p><b>OBJECTIVE</b>To investigate the degradation process of collagens and identify the key unit operation during manufacturing process of E'jiao.</p><p><b>METHOD</b>Samples in different unit operations were withdrawn, and their amino acid compositions and the molecular weight ranges were determined. The peptide composition was analyzed by high-performance liquid chromatography/mass spectrometry.</p><p><b>RESULT</b>The content of sample during atmospheric condensation unit increased by 16.8% compared to the thermal extraction unit. Gel filtration chromatographic analysis indicated that the degradation process of collagen primarily occurred during the atmospheric condensation unit. The peptides in samples mainly resulted from the degradation of collagens and cytoskeleton proteins such as tubulin, actinin, and so on. The relative abundance of degraded collagens increased with the decrease of no-collagen proteins.</p><p><b>CONCLUSION</b>Collagen degradation mainly occurred during the atmospheric condensation unit, which was the key process affecting the composition of E-jiao.</p>